I have seen after long - continued frost the course of a stream completely altered by this bottom-ice (as it is called here), and I have also seen a weir with a wall of ice on it three feet high (raised in a single night) by the same cause.

I am neither chemist nor meteorologist, and therefore I am not able to say much about radiation; but my idea of it is, that its effects in water would be much greater in still pools than in rapid streams, and that, therefore, if radiation was the cause of bottom-ice, there ought to be more of it in the pools than in the rapid streams.

I was not aware before seeing your remarks that either Arago or any other philosopher had ever written about bottom-ice, and even now I do not know what are their opinions on the subject, and if the discussions in your paper are to be settled by authority and not by argument, I can only make my bow and withdraw; but if it meets your views to allow your correspondents to state their opinions temperately, and support them by such arguments as occur to them, I do not yet feel inclined to give up my notions about bottom-ice.

You say at the end of remarks about bottom-ice that you cannot admit the soundness of my explanation, and that you are well aware of what is said by Arago and others on this curious phenomenon, and that bottom-ice has been observed in ponds when there was no breeze, and that the water in pools between the rapids of weirs can hardly ever be still enough to fall below the freezing-point, and yet remain fluid.